<!DOCTYPE html>
<html class="reftest-wait">
<head>
    <title></title>
</head>
<body>
<script type="text/javascript">
    function loadFrame() {
        let frame = document.getElementById('frame');
        frame.contentDocument.body.removeAttribute('lang');
        document.documentElement.className = "";
    }
</script>
<iframe id=frame onload="loadFrame()" src="data:text/html,<body lang='en'>text</body>" marginwidth="100px" marginheight="100px"  width=300px height=300px></iframe>
</body>
</html>